The Royal Swedish Academy of Sciences awarded the Nobel Prize in Physics 2020 on 6 October to three laureates for their discovery of a black hole in the universe. Roger Penrose showed the general theory of relativity leads to the formation of black holes, while Reinhard Genzel and Andrea Ghez discovered an invisible, extremely heavy object governs the orbits of stars at the centre of our galaxy. David Haviland, chairperson of the Nobel Committee for Physics, says a supermassive black hole is the only currently known explanation for the findings. Professor Göran K. Hansson, secretary general of the Royal Swedish Academy of Sciences, made the announcement of the 2020 Nobel Prize in Physics with an award of 10 million Swedish kronor.
“Penrose of the University of Oxford in the United Kingdom used ingenious mathematical methods in his proof that black holes are a direct consequence of Albert Einstein’s general theory of relativity. Einstein did not himself believe that black holes really exist, these super-heavyweight monsters that capture everything that enters them. Nothing can escape, not even light,” says Haviland.
According to the chairperson, in January 1965, 10 years after Einstein’s death, Penrose proved that black holes really can form and described them in detail. He says at their heart, black holes hide a singularity in which all the known laws of nature cease and Penrose’s article is still regarded as the most important contribution to the general theory of relativity since Einstein.
Genzel, of the Max Planck Institute for Extraterrestrial Physics, in Germany and the University of California, in the United States, and Ghez, of the University of California in Los Angeles, each lead a group of astronomers that since the early 1990s has focused on a region called Sagittarius A* at the centre of our galaxy. They have been mapping with increasing precision the orbits of the brightest stars closest to the middle of the Milky Way.
The chairperson says the measurements of these two groups agree with both groups finding an extremely heavy, invisible object that pulls on the jumble of stars causing them to rush around at dizzying speeds. He says around four million solar masses are packed together in a region no larger than our solar system and using the world’s largest telescopes, Genzel and Ghez have developed methods to see through huge clouds of interstellar gas and dust to the centre of the Milky Way.
According to Haviland, stretching the limits of technology, they refined new techniques to compensate for distortions caused by the Earth’s atmosphere, building unique instruments and committing themselves to long-term research. He says their pioneering work has given the most convincing evidence yet of a supermassive black hole at the centre of the Milky Way.
“The discoveries of this year’s Laureates have broken new ground in the study of compact and supermassive objects. But these exotic objects still pose many questions that beg for answers and motivate future research. Not only questions about their inner structure, but also questions about how to test our theory of gravity under the extreme conditions in the immediate vicinity of a black hole,” says Haviland.